Clinical thermometer



Dec.28,1948. L. EISELE 57 CLINICAL THERMOMETER Filed May 4, 1944 1 LOGAN Emma INVENTQR ATTORNEY Patented Dec. 28, 1948 OFFICE CLINICAL THERMQMETER 1 ogan Eisele, Nashville, Tenn. I Application May 4., 1944;:seria1 hcs534x64 r ,2 Claims. (01, 173 -351) This invention relates to clinical or self-registering thermometers. This type thermometer may be define'das one whichuporrbeing inserted in thebral or rectal cavity-Yer other place-the temperature of whichit isdesire'd to ascertain,

themereurycolumn will rise to the proper; point to indicate the temperature upon a suitable scale, usually engraved upon the thermometer stem, but, upon being removed from said cavity, the mercury column will maintain its position in the stem, thus allowing the reading to be made at any time subsequent to such removal, due to the fact that this type of thermometer includes a device which causes mercury column to separate into two parts at some point between the bulb and the scale, the lower part of the column receding into the bulb as the temperature of the thermometer falls to the ambient temperature, while leaving the upper portion of the mercury column in the highest position it reached during the time the thermometer was inserted in the cavity.

The device by which the mercury column is caused to divide or separate as the temperature of the bulb falls usually is called the contraction and usually consists of a small, partially collapsed bulb formed in the thermometer bore between the main bulb and the scale portion of the stem. The two opposite walls of said contraction bulb are collapsed against each other forming a bifurcated passage of reduced cross section as compared to the bore of the thermometer stem.

The contraction so formed constitutes such an obstruction to the movement of the mercury column that the cohesive force of the mercury is unable to pull the upper portion of the mercury column therethrough, thus causing the column to divide at the contraction.

The proper forming of this contraction requires great skill in manipulation, and even under optimum conditions a large percentage of rejects are The construction of my new form of clinical or self-registering thermometer contraction may best be understood by referring to the accompanying drawings in which:

Figure 1 is a partial longitudinal section of the thermometer of my invention.

. l ,2 .Fig-ures -3, and i .are cross sections taken alongthe-l-ine A-A of Figure 1, showing various optional forms the leakage openings, hereinafter described, may take. 4

-Referrin'g-now innrore detail to the-drawings the numeral; M: denotes the stem. of glass contain-1 ing the axially positioned capillary or bore I I. A suitable scale is engraved upon the surface of the stem I0 and shows, by the height of the top of the mercury column in bore I I, the temperature to which the bulb I2 of the thermometer is or has been subjected.

The bulb I2 is formed from a separate piece of glass from the stem I0 and at one end is formed into a neck I3 which carries at its distal end an enlargement, bulb or knob I4. The lower end of the stern H] is interiorly enlarged to form the cavity I5 open at its lower end. The stem I3 and enlargement Id of bulb I2 are inserted into cavity I5 and the bulb I2is welded or fused to the lower end of the stem by means of the circumferential weld I6. .An aperture I1 is formed in the wall of stem I3. The bulb I2 is filled with mercury, the remaining space is evacuated in the usual manner and the upper end of the stem is sealed off. The circumference of enlargement I4 is not a perfect fit in the interior of cavity I5, being of oval shape as shown in Figure 2 or having grooves formed therein as shown in Figures '3 and 4 or otherwise formed so that there remain small spaces I8 between the circumference of enlargement I4 and the inner surface of cavity I5 and these small spaces constitute the contraction or restriction to the flow of mercury which causes the mercury column to divide.

The operation of my new improved thermometer is as follows: Upon being subjected to an elevated temperature the mercury contained in bulb I2 expands and travels outward through aperture I1 and forces past the restrictions I8 between the enlargement I4 and the inner surface of cavity I5 into bore II thus indication by the position of the top of the column the temperature to which the bulb has been subjected. Upon being removed from the source of heat the mercury contained in bulb I2 contracts and the column divides in spaces I8, the lower part receding into the bulb and the upper part remaining in its indicating position.

After the reading has been taken the upper portion of the mercury column may be caused to rejoin that in the bulb by shaking it down in the usual manner.

It will be obvious that certain departure may be made from the details of construction shown 1 without departing from the spirit of my invention. For example, stem [3 and enlargement M may be solid instead of hollow as shown; the aper- 1 ture l1 may be positioned at any point between spaces l8 and weld l6 and may consist of a plu- 1 rality of apertures of any suitable size and shape. Numerous other variations all within the scope of my invention will be obvious to those skilled in the art.

Having thus described my invention, what I claim as new is:

1. A clinical or self-registering thermometer to said stem, said stem having a cavity in its lower end communicating with said bulb and said bore,

1 said bulb being formed at one end with a per-' 1 forated neck member which carries at its distal end an enlargement which extends into said cav ity, the outer surface of said enlargement and the inner surface of said'cavity defining there- 1 between small leakage openings of such size that 1 the forces of gravity and cohesion are unable to cause mercury to pass therethrough but at the same time large enough that a reasonable amount of shaking or slinging will cause mercury to pass comprising a stem portion having a small bore therethrough, a mercury containing bulb joined leakage passages.

4 therethrough, said bulb and said bore being partially filled with mercury and evacuated.

2. A clinical thermometer comprising a stem having a bore therethrough, a bulb joined to said stem, said stem having a cavity in its lower end between said bulb and said bore and communicating with said bulb and bore, said bulb being formed at one end with a neck member extending into said cavity and defining between its outer surface and the inner surface of the cavity small REFERENCES CITED The following references are of record in the 4 file of this patent:

UNITED STATES PATENTS Germany a Feb. 4, 1915 LOGAN EISELE." 

